USC safety Taylor Mays was thrilled with the symbolic meaning of the Trojans’ defense earning a shutout Saturday.

“In the defensive staff room, they put a skunk on the table when the other team doesn’t score,” Mays said. “They can put that skunk on there, finally.”

That skunk could also occupy a spot on a table in the offensive staff room, but for completely different reasons. The No.8-ranked Trojans turned in one of their ugliest quarters in recent history despite defeating Arizona State, 28-0, in front of an announced crowd of 85,956 at the Coliseum.

Quarterback Mark Sanchez, still considered a Heisman Trophy candidate in some circles, ended that long-shot hope with a third quarter that consisted of four turnovers (one fumble, three interceptions).

In Sanchez’s defense, one interception was not his fault, but this game served as a reminder that USC (4-1, 2-1) can afford to be erratic in a forgiving Pacific-10 Conference. That is a luxury teams like Texas, Oklahoma and LSU could hardly relate to Saturday.

“We have to learn from it,” USC offensive coordinator Steve Sarkisian said. “There will be a 24-21 game and we can’t turn it over five straight times. In a tight ballgame, we need to snap out of funks earlier.”

Even usually sunny USC coach Pete Carroll could not mask the frustration of the third quarter, when the Trojans outgained Arizona State in yardage, 34-14.

“God, it took forever,” Carroll said. “I kept waiting for something to happen so the fans would clap.”

USC almost cleared out some of its own fans in the third quarter, a tradition it developed on the road when it demoralized the opponents’ supporters.

Sanchez, who missed two days of practice with a bone bruise in his knee, quickly left the locker room and made only a few brief comments.

“It was a tough outing for me and the offense as a whole,” he said. “I think that we beat ourselves. We didn’t see anything that we weren’t prepared for. We just didn’t execute the way we would have liked.

“I didn’t make good decisions and didn’t make good throws.”

That was an understatement. Sanchez finished 13 for 26 for 179 yards with a touchdown and three interceptions.

Sarkisian was asked if Sanchez was physically limited.

“Not at all,” Sarkisian said. “Some balls got knocked around, and then you start to squeeze the ball like a pitcher.”

Carroll alternated between defending his quarterback and explaining the offensive deficiencies.

“Offensively we got out of whack. It was a hard game for Mark,” he said. “We did different formations, we changed the rhythm of the flow. We were frustrated.

“He was not as solid. He was physically well but wasn’t right. He was a little hesitant at times. It was incredible he played. I know it wasn’t a game he was proud of, but I’m proud as hell of the guy.”

Imagine if USC played that way against a real team and not an Arizona State offense that could barely function with an injured Rudy Carpenter (Westlake High) and little-used Danny Sullivan at quarterback.

“I can honestly say I don’t remember being this ineffective on offense in my entire career,” Arizona State coach Dennis Erickson said.

The Sun Devils (2-4, 1-2) tried to survive with Carpenter nursing a sore ankle, but he was forced to leave in the second half and give way to Sullivan, who had thrown for minus-1 yard entering the game.

“Nothing was working,” Carpenter said.

Perhaps no play demonstrated that more than reliable ASU kicker Thomas Weber sending a 29-yard field goal attempt into defensive tackle Fili Moala’s elbow. He followed that up with another attempt that was blocked by Moala.

“I’m very perplexed, we’re better than that,” Erickson said.

Arizona State’s inept offense prevented USC’s defense from feeling completely satisfied, especially with the Trojans offense turning the ball every series at one stage.

“I don’t think of it as a dominating performance because the momentum wasn’t with us the whole game,” USC defensive end Clay Matthews said.

The Trojans’ defense held Arizona State to 229 yards, including 154 passing, and outscored the Sun Devils 7-0 as cornerback Kevin Thomas intercepted a pass and returned it 46 yards for a touchdown. But Carroll was concerned about five defensive penalties.

“The penalty situation is horrible,” Carroll said. “I didn’t get it done. We’re still on it. We’ll have twice as many officials on the field next week in practice.”

But the bigger issue was a split-personality offense that looked utterly unimpressive for two of the past three games.

“The biggest issue we face is the turnover thing,” Carroll said. “On a day like this, we could easily lose.”